Generic milling drums are used in construction machines for grinding soil, in particular, in ground milling machines, stabilizers, recyclers and/or surface miners. Such construction machines are known for a road milling machine, for example, from DE 10 2010 014 529 A1, for a stabilizer/recycler, for example, from EP 2 423 384 A2, and for a surface miner, for example, from EP 2 236 745 A2, which are incorporated herein by reference. In this respect the present invention also relates to such a construction machine comprising a milling drum according to the present invention. Typical fields of use are, therefore, in the construction of roads and paths as well as in the extraction of natural resources. Under working conditions, the milling drum is allowed to descend, while rotating, into the subsoil and in so doing, it mills up ground material for mixing purposes and/or for the purpose of removal. Typically, a generic milling drum of this kind comprises a hollow cylindrical supporting barrel that extends along an axis of rotation and has an external cylindrical surface. The axis of rotation extends in a horizontal plane and at right angles to the direction of travel of the ground milling drum. The external cylindrical surface of the supporting barrel comprises a plurality of milling devices. The milling devices are in general the working components with which the milling work of the rotating milling drum is done, that is to say, they are the working components that are responsible for the milling process. Such a milling device comprises, for example, a milling chisel, more particularly, a pick, and an appropriate holder including, for example, a base part and a quick-change tool holder attached to the supporting barrel. Such a milling device is described, for example, in the patent applications DE 10 2010 044 649 A1, DE 10 2010 051 048 A1 and DE 10 2010 013 983 A1 of the Applicant, which are incorporated herein by reference with respect to the design and function of such a milling device. Normally the milling tools are distributed and located on the basis of a specific arrangement on the external cylindrical surface of the supporting barrel. This arrangement includes, for example, in the case of road milling devices and surface miners, an at least partially spiraled layout to facilitate transportation of the milled material in the axial direction of the axis of rotation of the milling drum under operating conditions such as is indicated in, for example, DE 10 2011 009 092 A1. Such transportation of the milled material in the axial direction is desirable, for example, when the milled material is to be transported to an ejection port of a milling drum case. To this end, for example, side walls of the milling devices, more particularly, of the holding devices, can be utilized. Furthermore, it is known to equip a generic milling drum with at least one material guiding device formed separately and locally detached so as to form a material guiding device specifically designed for guiding the milled material under working conditions. This can refer, for example, to so-called ejectors that facilitate material transportation in the direction of rotation of the milling drum and which are required to transport, in particular, milled material, in a manner similar to shovels, from the milling chamber in the direction of rotation of the milling drum to the ejection port. Such an ejector is disclosed, for example, in DE 10 2011 009 092 A1 which is also incorporated herein by reference. The direction of rotation of the milling drum refers here to the direction of rotation of the milling drum about its axis of rotation under operation conditions.
Practical use of such milling drums has proven, however, that the milling devices themselves and with that the holders for the milling tools are subject to significant wear, particularly, when there are large linear distances between the individual milling tools and/or when there are large distances between the tools within the spiral configuration. This makes it necessary to replace the milling devices after comparatively short operational periods in order to ensure flawless operation of the milling drums. The linear distance refers here to the distance between the tips of the milling tools in two milling devices positioned one behind the other, as regarded in the direction of rotation of the milling drum, and as measured in the axial direction of the axis of rotation of the milling drum, that is to say, to the offset or degree of stagger of two milling devices positioned one behind the other in the direction of rotation as measured in the axial direction of the axis of rotation of the milling drum. Large linear distances between the milling devices will thus be found especially when the milling drum is equipped with only comparatively few milling devices and/or when the spiral configuration of the milling devices shows a comparatively steep gradient. The distance between tools, however, refers to the distance between the tips of, or between the same fixed points of, the milling tools of two milling devices positioned one behind the other within a spiral configuration, as measured in the axial direction of the axis of rotation of the milling drum, that is to say, to the offset of two milling devices positioned one behind the other in the direction of rotation within a common spiral configuration, as measured in the axial direction of the axis of rotation of the milling drum.
It is known in the prior art to counteract this wear process by applying additional hard facing to parts of the milling devices, such as, in particular, to quick-change holders and base holders and also to integrate comparatively elaborate additional screw-type flights. These measures are elaborate and comparatively expensive since, for example, the comparatively expensive hard facing must as a rule be renewed annually.
Thus, the object of the present invention is to provide a generic milling drum which makes it possible to operate the machine at comparatively less expense, especially with reduced wear on the milling devices, and which simultaneously provides reliable guidance of the milled material in the axial direction of the milling drum.